1. Field of the Invention
This invention relates to dies that are used in presses for loading and reloading military, sporting arms and industrial ammunition cartridges.
2. Background Art
The established method for reloading ammunition cartridges comprises the following steps: resizing the brass cartridge case to reestablish the original size for receiving the corresponding type and size of bullet; depriming the case; expanding and/or flaring the case neck; repriming the cartridge with a fresh primer; refilling the case with propellant (black powder or smokeless gun powder); inserting the bullet to the prescribed depth within the case, and crimping the bullet in the case mouth. Dies corresponding to these steps are customarily screwed into the head of an ammunition reloading press. A sizing and decapping die is screwed into the reloading press in alignment with a lever-driven ram that drives the case into the sizing and decapping die. The case neck is then expanded with the sizing and decapping die for most rifle cases, but using a combination flaring and expanding die in a separate operation for a pistol and for a straight-walled rifle case. Next, a bullet seating operation is performed using a bullet seating die and the process is completed by imposing a roll crimp on the mouth of the case. From the middle of the 19th century to the present, cartridges that needed to be crimped were roll crimped in place to secure the bullet from movement within the case, either from recoil or the cartridge feeding process. In the middle 1970's, RCBS, Inc., of Oroville, Calif. invented the taper crimp die for use with rimless ammunition designed for semiautomatic pistols. Hence, in the case of ammunition for semiautomatic pistols, a taper crimp operation is performed on the reloaded case with a taper crimp die.
The present invention is directed to a die for imposing a taper crimp only. A taper crimp of appropriate degree serves to promote uniform burning of gun powder and provides improved accuracy; moreover, when imposed on ammunition for use in semiautomatic weapons, the taper crimp promotes better feed of cartridges through the weapon. The degree of taper is commonly expressed in thousandths of an inch of radial crimp per case axial inch, abbreviated as “TPI.” By planned and deliberate process, one can determine an optimal degree of taper crimp for a particular size and kind of ammunition, expressed in thousandths of an inch. The challenge then is to be able to reliably and repeatedly impose a prescribed degree of crimp upon reloaded ammunition cases. Prior to my invention, no simple, reliable and repeatable method and no suitable taper crimp die existed for achieving that purpose.